Correlation between reduced work speed and noise annoyance due to exposure to low-frequency noises

 Low-frequency sounds are generated from many sources in both the occupational and nonoccupational environments. Hence, the aim of this study was to investigate the effect of low-frequency noise (LFN) on the working speed and the rate of annoyance of the subjects under study. Materials and 

 This cross-sectional/interventional study was performed in the sound and vibration laboratory of Isfahan University of Medical Sciences in 2019. Simple random sampling was used to select the subjects. In this study, the working speed of the subjects was evaluated using mental arithmetic test and the rate of the perceived annoyance was measured using ISO 15666 in Likert format (0–11) due to exposure to noise sources. Mann–Whitney U-test was used to analyze the data. 

 There was a significant statistical difference in the rate of the individuals' working speed Between 0 and 90 min at the frequency of 125 Hz and the sound level of 95 dB (P = 0.029). There was a statistically significant difference between the frequencies of 125 and 1000 Hz at the sound pressure level of 85 dB and the 45 min time (P = 0.001) and 90 min (P = 0.001) as well as at the 95 dB sound pressure level at 45 min (P = 001) and 90 min (P = 0.001). 

 The results of the present study showed that increasing sound pressure levels and the exposure time in both LFN and high-frequency noises, increased the working speed and the amount of perceived annoyance in individuals.